newlib/libc/stdlib/getenv.c

   1 /*
   2 FUNCTION
   3 <<getenv>>---look up environment variable
   4
   5 INDEX
   6         getenv
   7 INDEX
   8         environ
   9
  10 SYNOPSIS
  11         #include <stdlib.h>
  12         char *getenv(const char *<[name]>);
  13
  14 DESCRIPTION
  15 <<getenv>> searches the list of environment variable names and values
  16 (using the global pointer ``<<char **environ>>'') for a variable whose
  17 name matches the string at <[name]>.  If a variable name matches,
  18 <<getenv>> returns a pointer to the associated value.
  19
  20 RETURNS
  21 A pointer to the (string) value of the environment variable, or
  22 <<NULL>> if there is no such environment variable.
  23
  24 PORTABILITY
  25 <<getenv>> is ANSI, but the rules for properly forming names of environment
  26 variables vary from one system to another.
  27
  28 <<getenv>> requires a global pointer <<environ>>.
  29 */
  30
  31 /*
  32  * Copyright (c) 1987, 2000 Regents of the University of California.
  33  * All rights reserved.
  34  *
  35  * Redistribution and use in source and binary forms are permitted
  36  * provided that: (1) source distributions retain this entire copyright
  37  * notice and comment, and (2) distributions including binaries display
  38  * the following acknowledgement:  ``This product includes software
  39  * developed by the University of California, Berkeley and its contributors''
  40  * in the documentation or other materials provided with the distribution.
  41  * Neither the name of the University nor the names of its
  42  * contributors may be used to endorse or promote products derived
  43  * from this software without specific prior written permission.
  44  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  45  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  46  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  47  */
  48
  49 #ifndef _REENT_ONLY
  50
  51 #include <stdlib.h>
  52 #include <stddef.h>
  53 #include <string.h>
  54
  55 /*
  56  * _findenv --
  57  *      Returns pointer to value associated with name, if any, else NULL.
  58  *      Sets offset to be the offset of the name/value combination in the
  59  *      environmental array, for use by setenv(3) and unsetenv(3).
  60  *      Explicitly removes '=' in argument name.
  61  *
  62  *      This routine *should* be a static; don't use it.
  63  */
  64
  65 char *
  66 _findenv (register const char *name,
  67         int *offset)
  68 {
  69   return _findenv_r (_REENT, name, offset);
  70 }
  71
  72 /*
  73  * getenv --
  74  *      Returns ptr to value associated with name, if any, else NULL.
  75  */
  76
  77 char *
  78 getenv (const char *name)
  79 {
  80   int offset;
  81
  82   return _findenv_r (_REENT, name, &offset);
  83 }
  84
  85 #endif /* !_REENT_ONLY */